Toilet paper

ABSTRACT

Provided is toilet paper which is excellent in thickness feeling and water disintegrability, has sufficient softness, gives a sense of security for human bodies during use, and is environmentally friendly. 
     Toilet paper has three or four plies. The basis weight is 12.5 to 15.5 g/m 2  per ply. 80 to 100 mass % of fiber is softwood kraft pulp that is subjected to oxygen pulping and is not bleached with chlorine. The toilet paper contains a cationic fatty acid amide-based softener, and has a paper thickness of 120 to 150 μm per ply, a paper thickness of 400 to 600 μm as a whole of the toilet paper, and a water disintegrability of 10 seconds or less.

TECHNICAL FIELD

The present invention relates to toilet paper.

BACKGROUND ART

With the spread of shower toilets, which are also called toilets with awashing function, toilet paper is also required to be suitable for usein shower toilets (Patent Literature 1 below).

It is desirable that toilet paper suitable for shower toilets be aproduct with multiple plies such as three plies or four plies, whichgives a sense of security when used by a consumer.

Toilet paper is generally produced from a fiber raw material obtained bymixing hardwood-derived pulp having a short fiber length andsoftwood-derived pulp having a long fiber length, and principally,common toilet paper contains a large amount of hardwood-derived pulpthat likely improves softness and surface properties.

In addition, in order to enhance the whiteness, pulp, which is a fiberraw material, is bleached with a chlorine-based bleaching chemical suchas chlorine, chlorine dioxide or sodium hypochlorite, and consumersgiving great importance to a sense of security for human bodies andenvironmental consideration desire environmentally friendly products inwhich pulp free of a chlorine-based bleaching chemical is used as a rawmaterial.

CITATION LIST Patent Literature Patent Literature 1: JP 2011-153387 ASUMMARY OF INVENTION Technical Problem

However, in pulp that has not been bleached with a chlorine-basedbleaching chemical, a large amount of lignin remains, and fiber is hard,and toilet paper obtained using the pulp as a main fiber raw material islikely to give a feeling of hardness or surface roughness.

On the other hand, it is known that the strength of the paper isdecreased by increasing the blending amount of hardwood pulp for easilygiving a feeling of softness, but when the blending amount of hardwoodpulp is increased, water disintegrability is likely to deteriorate. Inthe case of multi-ply products, water disintegrability is likely todeteriorate in particular, and therefore when the blending amount ofhardwood pulp is increased, the toilet paper may be unsuitable for usein shower toilets.

Accordingly, a main object of the present invention is to provide toiletpaper which gives a thickness feeling providing security when used in ashower toilet, has sufficient softness, is excellent in waterdisintegrability, and gives a sense of security for human bodies duringuse.

Solution to Problem

The first means for achieving the above-described object is toilet paperhaving three or four plies, in which

80 to 100 mass % of fiber is softwood kraft pulp that is subjected tooxygen pulping and is not bleached with chlorine,

the toilet paper containing a cationic fatty acid amide-based softener,and

having a basis weight of 12.5 to 16.0 g/m² per ply,

a paper thickness of 120 to 150 μm per ply,

a paper thickness of 400 to 600 μm as a whole of the toilet paper, and

a water disintegrability of 10 seconds or less.

Advantageous Effects of Invention

Thus, according to the present invention, there is provided toilet paperwhich gives a thickness feeling providing security when used in a showertoilet, has sufficient softness, is excellent in water disintegrability,and gives a sense of security for human bodies during use.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of embosses according to an embodiment of thepresent invention.

FIG. 2 is a schematic diagram for illustrating a procedure for measuringan emboss depth according to the present invention.

FIG. 3 is a perspective view of a toilet roll according to an embodimentof the present invention.

DESCRIPTION OF EMBODIMENTS

The toilet paper according to an embodiment has three plies or fourplies. That is, three or four sheets are stacked. When the toilet paperhas multiple plies including more than two plies, such as three plies orfour plies, the overall paper thickness is large while each ply is thin,and the toilet paper hardly breaks and gives a sense of security whileit is likely to feel “soft” in particular.

If the toilet paper has two plies, it is difficult to develop athickness feeling, and the toilet paper lacks a sense of security whenwiping is performed while a large amount of water is absorbed after useof a shower toilet. When the toilet paper has five or more plies, it isdifficult to feel the softness during cleaning of the skin even wheneach ply is thinned. In addition, when the number of plies is five ormore while the basis weight and the paper thickness per ply are setaccording to the present invention as described later, and inparticular, embosses are applied, the rigid feeling is intensified, andit is difficult to feel the softness.

On the other hand, the toilet paper according to this embodiment has abasis weight of 12.5 g/m² or more and 16.2 g/m² or less per ply. If thebasis weight of one ply is within this range, when the toilet paper hasthree or four plies, sufficient resistance to breakage and a good feelagainst the skin can be obtained, and water disintegrability is easilydeveloped.

On the other hand, in the toilet paper according to the presentinvention, 80 to 100 mass %, particularly 100 mass %, of the constituentfiber is softwood kraft pulp which is subjected to oxygen pulping and isnot bleached with chlorine. More specifically, this softwood kraft pulp,which is also called NOKP, is produced by oxygen pulping continuouslyperformed in a continuous pulping kettle, and is not subsequentlybleached with a chlorine-based bleaching chemical in particular. Here,kraft pulp (KP) used for toilet paper includes bleached and unbleachedkraft pulp, and unbleached kraft pulp contains a large amount of lignin.The softwood kraft pulp used in the present invention is not bleachedwith a chlorine-based bleaching chemical, but is subjected to oxygenpulping (removal lignin with oxygen), so that about half of the ligninis removed. The chlorine-based bleaching chemical includes not onlychlorine but also chlorine dioxide and sodium hypochlorite. Thus, theECF pulp is not the softwood kraft pulp used in the present invention.

The toilet paper according to the present invention contains 80 to 100mass % of softwood kraft pulp which is not bleached with achlorine-based bleaching chemical and is subjected to lignin removaltreatment by oxygen pulping. That is, the toilet paper is produced usingsuch softwood kraft pulp as a main fiber raw material, particularly asall of fiber raw materials, and therefore gives a sense of security forhuman bodies during use and it is environmentally friendly. Inparticular, toilet paper containing 80 to 100 mass % of such softwoodkraft pulp is light brown and thus apt to look like a natural productwhich has not been chemically treated. Also, such toilet paper gives animpression of being soft. Therefore, a purchaser has a great sense ofsecurity.

On the other hand, since lignin removal treatment by oxygen pulpingreduces the amount of lignin to about half of that before the oxygenpulping, it is easier to develop softness and obtain high strength ascompared to a case where pulp which is not subjected to lignin removaltreatment at all is used as a raw material. In addition, since theamount of hardwood kraft pulp, whose water disintegrability is apt todecrease, is at most less than 20 mass %, particularly 0 mass %, it iseasy to improve water disintegrability.

In addition, since lignin is not hydrophilic, lignin-containing softwoodkraft pulp which is subjected to oxygen pulping and is not bleached withchlorine has low fiber swellability and weak interfiber bonding. Thus,the fibers become less dense, so that water disintegrability isimproved. Further, an excellent cushioning property is obtained becausesoftwood kraft pulp is derived from softwood and thus has a longer fiberlength than that of pulp derived from hardwood and because lignin has anaction of preventing densification of the fibers.

The toilet paper according to the present invention contains 80 to 100mass % of the softwood kraft pulp and has a basis weight of 12.5 to 16.0g/m² per ply. The basis weight per ply is more preferably 12.7 to 15.8g/m². The basis weight according to the present invention is based onthe basis weight measurement method of JIS P 8124 (1998). When thetoilet paper contains 80 to 100 mass % of the softwood kraft pulp, andhas a slightly low basis weight per ply of 12.5 to 15.5 g/m², andmultiple plies such as three plies or four plies, the toilet paper isexcellent in thickness feeling and water disintegrability, easilydevelops softness, gives a sense of security for human bodies duringuse, and is environmentally friendly. Here, other pulp fibers formingthe toilet paper according to the present invention are not necessarilylimited. The pulp fiber may be virgin pulp or used paper pulp. In thestep of regenerating pulp from used paper, the used paper pulp tends tohave finer fiber than the pulp fiber before the regeneration, and due tosuch a property of the fiber, the fiber is easily densified to enhancethe paper strength without increasing the paper thickness. On the otherhand, if used paper pulp is blended in an excessive amount, textureproperties such as flexibility deteriorate. Thus, in consideration ofthe characteristics of used paper pulp, the blending ratio may be setwithin the range of 0 to less than 20 mass %. The type of used paperpulp is not necessarily limited, and used paper pulp with milk cartonused paper or high-quality used paper is particularly desirable. Usedpaper pulp contains a large amount of hardwood kraft pulp (LBKP) derivedfrom a raw material, so that it is easy to develop paper strength.

On the other hand, it is desirable that the toilet paper according tothe present invention be moisturizer-non-coated toilet papersubstantially not coated with a moisturizer. The moisturizer as anexternal additive according to the present invention is a polyol, andincludes at least glycerin, diglycerin, propylene glycol, 1,3-butyleneglycol and polyethylene glycol. However, the toilet paper may containthe above-described components as long as their effect is not worthy ofgiving the toilet paper a moisture-retaining property. The toilet paperaccording to the present invention is excellent in sense of security forhuman bodies, and when a moisturizer is applied, a sticky feeling and amoist feeling peculiar to the moisturizer arise, so that the sense ofsecurity for human bodies decreases.

On the other hand, a softener or a softening moisturizer, thatdetermines the softness and paper strength of the base paper itself, isinternally added during papermaking to the toilet paper according to thepresent invention. The softener contained in the toilet paper accordingto the present invention is a cationic fatty acid amide-based softener.The toilet paper according to the present invention preferably containsthis cationic fatty acid amide-based softener. The cationic fatty acidamide-based softener does not undergo a decrease in effect due to thepresence of lignin, and acts to coat the fiber surface. Accordingly,even when pulp containing lignin is blended at a high ratio, the surfaceis smooth, the stiff feeling markedly decreases, and the fullness isenhanced. As a specific example of the cationic fatty acid amide-basedsoftener, a reaction product of epihalohydrin with an amide-basedcompound obtained by reaction of a polyalkylene polyamine with amonocarboxylic acid is desirable. The effect is exhibited when thiscationic fatty acid amide-based softener is used. In internal additionof a reaction product of epihalohydrin with an amide-based compoundobtained by reaction of a polyalkylene polyamine with a monocarboxylicacid, it is preferable that the reaction product is mixed with anemulsifier having an alkyl group and/or an alkylene group with 4 to 20carbon atoms, and water, followed by addition of the mixture. Thecontent of the cationic fatty acid amide-based softener is notnecessarily limited, and when the fixing rate is 50 to 60%, the amountadded during production may be 0.5 to 4.0 kg/ton of pulp.

Further, it is desirable that a softening moisturizer be internallyadded to the toilet paper according to the present invention. It isdesirable that the content be 0.2 to 2.0 kg/ton of pulp. Presence of asoftening moisturizer improves flexibility. The softening moisturizer isparticularly preferably a reaction product obtained by reacting a higherfatty acid with 12 to 24 carbon atoms and/or an ester compound of ahigher fatty acid with 12 to 24 carbon atoms with a compound obtained byadding an alkylene oxide with 2 to 4 carbon atoms to active hydrogen ofa polyalkyleneimine with a weight average molecular weight of 500 to10,000. Presence of the softening moisturizer further improves softness.

Here, the toilet paper according to the present invention may beembossed. The embossed pattern is not necessarily limited. The embossescan be applied in an appropriate embossed pattern such as microembosses,dot-shaped embosses or design embosses. However, it is desirable thatthe embossed pattern according to the present invention be that ofembosses applied in a ply-laminated state, which are called singleembosses.

A suitable embossed pattern according to the present invention has aconcave area of 1.0 to 2.5 mm², a density of 5.0 to 50 pieces/cm² and anemboss depth of 0.05 to 0.5 mm. The softness as toilet paper isimproved, and the softness in a rolled state like that of a toilet rollis enhanced, so that the toilet paper is likely to feel soft when aconsumer holds it in the hand. In particular, as shown in FIG. 1,concaves 31 having a square bottom surface with diagonal lineL4×diagonal line L4=1.0 to 1.5×1.0 to 1.5 mm (FIG. 1A) or substantiallysquare concaves 32 in which the four corners of the square extenddiagonally outward (FIG. 1B) are arranged in a grid pattern with acenter spacing L5 of 4.5 to 5.5 mm and an arrangement angle of 45° withrespect to the width direction, over the entire plane of paper, andvalley line portions 33 extending from the four corners of the concaveare present between the concave 31 (32) and the concave 31 (32). It isdesirable that the valley line portion 33 be gradually gently arrangedin an arch shape at a cross-section so as to be deepest at the fourcorners of the concave 31 (32) and shallowest at the middle pointbetween the concaves. This embossed pattern is excellent in softness andstool wiping property.

The emboss depth is measured by a one-shot 3D measurement macroscopeVR-3200 manufactured by KEYENCE CORPORATION or its equivalent, and theimage analysis software “VR-H1A” or its equivalent software. Themeasurement is performed under the conditions of a magnification of 12times and a viewing area of 24 mm×18 mm. However, the magnification andthe viewing area can be appropriately changed depending on the size ofthe emboss (concave). The specific measurement procedure will bedescribed with reference to FIG. 2. By use of the above-describedsoftware, an emboss depth (measured cross-section curve) profile at aline segment Q1 crossing the longest part of the peripheral edge of oneemboss (concave) 40 in the image part (X part in the figure) shown inplan view. In the “contour curve Q2” of the image part (Y part in thefigure) shown in sectional view, which is obtained by removing thecomponent of surface roughness at a wavelength shorter than λc: 800 μm(λc is a “filter for defining a boundary between a roughness componentand a wave component” as described in JIS-B0601 “3.1.1.2”) from thecross-sectional curve of the emboss depth profile, a minimum value oftwo concave edge points P1 and P2 projected upward and most sharplycurved and a region sandwiched between the concave edge points P1 and P2is determined, and taken as a minimum depth value Min. Further, theaverage of the depth values of the concave edge points P1 and P2 istaken as a maximum depth value Max. In this way, the emboss depth isdetermined from: emboss depth=maximum value Max−minimum value Min.Further, the distance (length) of the concave edge points P1 and P2 onthe X-Y plane is taken as a length of the longest part. In addition, thetwo concave edge points P1 and P2 projected and most sharply curved arevisually selected. In the selection, reference may be made to a contourE in the image in plan view of the emboss (concave) 40 during themeasurement. Similarly, the emboss (concave) depth is measured for theshortest part in a direction perpendicular to the longest part, and thevalue of a larger depth is adopted as the emboss (concave) depth. Theabove measurement is performed for any 10 embosses on the surface of thetoilet paper, and an average thereof is taken as the final emboss depth.

For the areas of individual concaves of the emboss pattern, the contourof the emboss concave is visually confirmed from a 3D image obtained byperforming measurement with a one-shot 3D measurement macroscope VR-3200manufactured by KEYENCE CORPORATION or its equivalent, and the imageanalysis software “VR-H1A” or its equivalent software, and the areainside the contour is measured. The measurement is performed for any 10embosses on the surface of the toilet paper, and an average thereof istaken as the final emboss area.

On the other hand, the toilet paper according to the present inventionhas a paper thickness of 120 to 150 μm per ply, and a paper thickness of400 to 600 μm as a whole of the toilet paper. When the paper thicknessis in this range, the softness is improved. The method for measuring thepaper thickness of toilet paper includes sufficientlyhumidity-conditioning a test piece under the conditions of JIS P 8111(1998) (usually about 8 hours), and then performing measurement in aone-ply state by use of a dial thickness gauge (thickness measuringinstrument) “PEACOCK G Type” (manufactured by OZAKI MFG. CO., LTD.)under the same conditions. Specifically, it is confirmed that dust, dirtor the like is not present between a plunger and a measuring table, theplunger is placed on the measuring table, the scale on the dialthickness gauge is moved to set to the zero point, the plunger is thenraised to place a sample on a sample table, the plunger is slowly moveddown, and the gauge at this time is read. When the toilet paper isembossed, it is ensured that one concave (convex) is within the range ofthe measuring table. When there are concaves having different depths, itis ensured that a concave having the deepest depth is within theabove-mentioned range. During the measurement, the plunger is merelyplaced, and is not pressed. The terminal of the plunger is made ofmetal. A circular plane with a diameter of 10 mm perpendicularly hitsthe plane of paper, and the load during the measurement the paperthickness is about 70 gf. The paper thickness is an average of valuesobtained by performing measurement 10 times. Here, during measurement ofthe paper thickness, there may be collapsed embosses (concaves), but thepaper thickness in the present invention is a value obtained bymeasuring the values including those of such collapsed embosses, andsuch collapse may be ignored. In the measurement of the paper thickness,a paper thickness difference caused by collapse of concaves can beignored.

In addition, the toilet paper according to the present invention is veryrapidly hydrolyzed with the water disintegrability being 10 seconds orless. This is because 80 mass % or more, particularly 100 mass %, of theconstituent fiber is softwood kraft pulp containing lignin, so that thefiber is easily loosened. When the water disintegrability is 10 secondsor less, the risk of clogging pipes at the time of disposition byrunning water in a flush toilet or the like dramatically decreases. Thewater disintegrability (easiness of loosening) is measured in accordancewith JIS P 4501 (1993). For the test on easiness of loosening, a 300 mLbeaker containing 300 mL of water (water temperature 20±5° C.) is placedon a magnetic stirrer, and the rotation speed of the rotor is adjustedto 600±10 rotations/minute. A square test piece 100±2 mm on a side isput into the beaker, and the stopwatch is started. The rotation speed ofthe rotor once decreases to about 500 rotations due to the resistance ofthe test piece, and the rotation speed increases as the test piece isloosened. The time when the rotation speed recovers to 540 rotations,the stopwatch is stopped, and the time is measured on a second-by-secondbasis. The test is conducted five times, and an average thereof is takenas a result of ease of loosening. The rotor has a disk shape with adiameter of 35 mm and a thickness of 12 mm.

It is desirable that the toilet paper according to the present inventionbe one in which the Canadian standard freshness of the papermaking rawmaterial is 650 cc or more. When the Canadian standard freshness of thepapermaking raw material is 650 cc or more, the pulp fiber is hardlybeaten, or fiber from an unbeaten raw material, and therefore toiletpaper further excellent in water disintegrability is easily obtained.

Here, it is desirable that the toilet paper according to the presentinvention have a dry tensile strength of 400 cN/25 mm or more and 900cN/25 mm or less in a longitudinal direction. It is desirable that thedry tensile strength in a lateral direction be 200 cN/25 mm or more and450 cN/25 mm or less. The toilet paper can be sufficiently used as longas the dry tensile strength is within the above-mentioned range.

The longitudinal direction of the paper, which is also called a MDdirection, is a flow direction during papermaking. The lateral directionof the paper, which is also called a CD direction, is a directionorthogonal to the flow direction (MD direction) during papermaking. Thedry tensile strength according to the present invention is a valuemeasured in accordance with JIS P 8113 (2006). The measurement isperformed in the following manner. As a test piece, one obtained bycutting the paper to approximately a width of 25 mm (±0.5 mm)×length of150 mm in both longitudinal and lateral directions, is used. The testpiece is measured as it has a plurality of plies. As a testing machine,a load cell tensile testing machine TG-200N manufactured by Minebea Inc.or a machine equivalent thereto is used. The grip interval is set to 100mm, and the tensile speed is set to 100 mm/min. The measurement isperformed in accordance with a procedure in which the test piece istightly fastened at both ends to a grip of the testing machine, atensile load is applied to the paper piece in an up-down direction, andan indicated value (digital value) is read at the time when the paperbreaks. For each of the longitudinal direction and the lateraldirection, five samples are prepared, measurement is performed fivetimes, and an average of the measured values is taken as a dry tensilestrength in each of the directions. For the product, the dry tensilestrength was measured with a plurality of sheets stacked to coincidewith the number of plies of the product. For the base paper, the drytensile strength was measured with a plurality of sheets stacked tocoincide with the number of plies of the product.

In addition, it is desirable that the toilet paper according to thepresent invention have a wet tensile strength of 50 cN/25 mm or more and100 cN/25 mm or less in a longitudinal direction. It is desirable thatthe wet tensile strength in a lateral direction be 25 cN/25 mm or moreand 50 cN/25 mm or less. The wet tensile strength is a value measured inaccordance with JIS P 8135 (1998). The measurement is performed in thefollowing manner. A test piece cut to approximately a width of 25 mm(±0.5 mm)×length of 150 mm in both longitudinal and lateral directions.When having a plurality of plies, the tissue paper is measured as it hasa plurality of plies. As a testing machine, a load cell tensile testingmachine TG-200N manufactured by Minebea Inc. or a machine equivalentthereto is used. The grip interval is set to 100 mm, and the tensilespeed is set to 50 mm/min. As the test piece, one cured with a dryer at105° C. for 10 minutes is used. The measurement is performed inaccordance with a procedure in which the test piece is tightly fastenedat both ends to a grip of the testing machine, water is thenhorizontally applied to the central part of the test piece with a widthof about 10 mm, a tensile load is then immediately applied to the paperpiece in an up-down direction, and an indicated value (digital value) isread at the time when the paper breaks. For each of the longitudinaldirection and the lateral direction, five samples are prepared,measurement is performed five times, and an average of the measuredvalues is taken as a wet tensile strength in each of the directions. Forthe wet tensile strength, the wet tensile strength was measured with aplurality of sheets stacked to coincide with the number of plies of theproduct.

It is desirable that the toilet paper according to the present inventionbe one in which the MMD value that is an index showing surfaceproperties is 7.5 or more and 9.5 or less. If MMD is less than 7.5, thesurface is excessively slippery, so that the wiping propertydeteriorates. If MMD is more than 9.5, the toilet paper may be poor intexture, and thus unsuitable for its use purpose. In the measurement ofMMD, the surface of a friction element is brought into contact under acontact pressure of 25 g with the surface of a measurement sample givena tension of 20 g/cm in a predetermined direction, and is simultaneouslymoved by 2 cm at a speed of 0.1 cm/s in a direction substantiallyidentical to the direction in which the tension is given, and thecoefficient of friction at this time is measured by use of a frictionalfeeling tester KES-SE (manufactured by KATO TECH CO., LTD.) or anequivalent machine. The value obtained by dividing the coefficient offriction by the friction distance (movement distance=2 cm) is MMD. Thefriction element is formed by mutually adjacent 20 piano wires P eachhaving a diameter of 0.5 mm, and has a contact surface formed so as tohave a length of 10 mm and a width of 10 mm. The contact surface isprovided with a unit bulge portion having a tip formed by 20 piano wiresP (curvature radius is 0.25 mm).

It is desirable that the toilet paper of this embodiment preferably havea softness of 1.8 cN/100 mm or more and 3.5 cN/100 mm or less. Thesoftness is one of the indices of softness, and the lower the value ofthe softness, the softer the product. The tissue paper or the toiletpaper is considered sufficiently soft when the value of the softness is1.0 cN/100 mm or less. The softness is a value measured on the basis ofa handle-o-meter method conforming to the JIS L 1096E method (1990). Thesize of the test piece is 100 mm×100 mm, and the clearance is 5 mm. Ineach of the longitudinal direction and the lateral direction,measurement is performed five times per ply. An average of a total of 10measurements is taken as the softness. The softness has no unit, but maybe expressed in a unit of cN/100 mm with consideration given to the sizeof the test piece.

In the toilet paper of the present embodiment, the dry tensile strengthand the wet tensile strength can be adjusted without use of a dry paperstrength enhancer or a wet paper strength enhancer. It is desirable thatin particular, the toilet paper be free of the paper strength enhancerfrom the viewpoint of a sense of security for users. The toilet paperaccording to the present invention contains softwood kraft pulp having alarge fiber length in a large amount of 80 mass % or more, particularly100 mass %, and therefore even when a paper strength enhancer is notcontained, entanglement of fibers can be secured to obtain strengthsufficient for use. In addition, the toilet paper contains lignin, andis therefore excellent in water disintegrability. That is, sufficientstrength can be secured without use of a paper strength enhancer, andwater disintegrability can be improved.

In the toilet paper of this embodiment, it is desirable to prevent useof a dry paper strength enhancer or a wet paper strength enhancer asdescribed above, but such an agent may be used as necessary as long asthe water disintegrability is not impaired. Examples of the dry paperstrength enhancer as used herein include starch, polyacrylamide, CMC(carboxymethyl cellulose), and sodium carboxymethyl cellulose, calciumcarboxymethyl cellulose and zinc carboxymethyl cellulose which are saltsof CMC.

Examples of the wetting paper strength enhancer include polyamidepolyamine epichlorohydrin resins, urea resins, acid colloid/melamineresins, heat-crosslinkable coating PAM, TS-20 manufactured by Seiko PMCCorporation, polymer-aldehyde functional compounds such as glyoxylatedpolyacrylamide and cationic glyoxylated polyacrylamide, copolymers ofacrylamide monomers obtained by modifying glyoxal with divalent aldehydeand other copolymerizable unsaturated monomers, and dialdehyde starch.

On the other hand, the toilet paper of this embodiment is suitable forformation of a toilet roll in which a strip-shaped toilet paper 10 iswound around a paper tube (also referred to as a tube core) 20 in a rollshape as shown in FIG. 3.

It is desirable that the toilet roll according to the present inventionhave a winding diameter L2 (diameter) of 110 to 115 mm. The windingdiameter of the toilet roll is defined as 120 mm or less in JIS P 4501,and a holder for setting a general toilet roll is prepared on the basisthat the winding diameter is 120 mm. The toilet roll of the presentinvention, which has a winding diameter of 110 to 115 mm, is sized to bethoroughly settable in a general holder. Here, the winding diameter is avalue measured by use of a diameter rule manufactured by MURATEC-KDSCorp. or an equivalent machine. The measured value is an average ofmeasurements made at three different positions in a width direction. Theaverage in products of the same production lot is an average for fiverolls.

On the other hand, it is desirable that the winding length of the toiletroll be 20 to 40 m, and here it is desirable that the winding density be0.20 to 0.30 m/cm². The winding density here is a value calculated fromthe formula: winding length (m)÷actual cross-sectional area. The actualcross-sectional area is calculated from the formula: {(rolldiameter/2)×(roll diameter/2)×π−(paper tube outer diameter/2)×(papertube outer diameter/2)×π} (unit; cm²). That is, actual cross-sectionalarea is an area obtained by subtracting the lateral surface area of theopening of the paper tube from the area of the end surface. When havinga winding density of 0.20 to 0.28 m/cm² in the above-described rollform, the toilet paper according to the present invention feels markedlysoft when the peripheral surface of the roll is held in a hand. It isdesirable that the outer diameter of the paper tube (paper tubediameter) L3 be 35 to 45 mmφ, similarly to a general size.

In addition, in the toilet paper of the present invention, it isdesirable that the winding hardness of the roll be 1.8 to 2.2 mm. “HandyCompression Tester KES-G5” manufactured by KATO TECH CO., LTD. is usedfor measuring the winding hardness (mm) (T0-TM) of the roll. The toiletroll TR is horizontally placed on a horizontal pedestal formed of asteel plate in such a manner that the central axis of the toilet paperis horizontal, and a steel plate terminal having a circular plane with acompression area of 2 cm² is brought into contact with the center of theupper surface of the outer periphery of the roll trunk. This contactstate is taken as a zero point, and the steel plate terminal is movedvertically downward from such a zero point at a speed of 10 mm/min tocompress the toilet roll. The amount of pressing at a compressive loadof 0.5 gf/cm² is T0 (mm), the amount of pressing at a compressive loadof 50 gf/cm² is TM (mm), and (T0-TM) (mm) is the winding hardness of theroll. When the winding hardness (mm) of the roll increases, the pressingdepth at the time of pressing the roll to 50 gf/cm² increases, and theroll has fluffy paper quality. That is, the winding hardness of the rollcorresponds to a fullness. When the winding length and the windingdensity are as described above, such a winding hardness can bethoroughly obtained.

Further, it is desirable that the toilet roll of the present inventionhave a compression work amount (WC) of 3.6 to 4.6 gf·cm/cm². Thecompression work amount (WC) is a work amount when the steel plateterminal is brought into contact with the roll at 0.5 gf/cm² and thenpressed to 50 gf/cm². When the compression work amount (WC) increases,the repulsive force at the initial stage of pressing decreases, so thatthe roll feels soft at the instance when the roll is grasped, and whenthe roll is subsequently pressed to a large depth under a compressionload of 50 gf/cm² at which the roll is normally held, the roll can beevaluated as being soft and fluffy in quality.

In the toilet paper according to the present invention, 80 to 100 mass %of fiber is softwood kraft pulp which is subjected to oxygen pulping andis not bleached with chlorine and which contains lignin and has a largefiber length, and interfiber bonding is weak, so that in theabove-described roll form, the toilet paper is excellent in cushioningproperty, and likely to feel soft when held in a hand as describedabove.

Hereinafter, the effects of the toilet paper according to the presentinvention will be further described with reference to examples.

EXAMPLES

Sensory evaluation was performed on “softness”, “fullness”, “thicknessfeeling” and “breakage and strength during use” for examples of thetoilet paper of the present invention and comparative examples.

The configuration of the toilet roll and the physical properties andcomposition of the toilet paper according to each example are shown inTable 1 below.

For the sensory evaluation, 18 subjects actually used the rolled toiletpaper of each example, and relative evaluation was performed on theitems of “softness”, “fullness”, “thickness feeling” and “tear strengthduring use” with respect to Comparative Example 3 (conventionalproduct). In the evaluation, Comparative Example 3 was given a score offour points (median), and scores were given at intervals of one pointwhere the highest score was set to seven points and the lowest score wasset to one point. An average of the scores was calculated.

TABLE 1 Compar- Compar- Compar- Compar- Compar- ative ative ative ativeative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2ple 3 ple 4 ple 1 ple 2 ple 3 ple 4 ple 5 Bleached/ Un- Un- Un- Un-Bleached Un- Un- Un- Un- unbleached bleached bleached bleached bleachedbleached bleached bleached bleached Pulp NUKP % 0 0 0 0 0 — — — — NOKP100 100 100 100 0 — — — — NBKP 0 0 0 0 35 — — — — LUKP 0 0 0 0 0 — — — —LOKP 0 0 0 0 0 — — — — LBKP 0 0 0 0 65 — — — — Freeness Un- Un- Un- Un-430 cc — — — — beaten beaten beaten beaten Softener Fatty acid- kg/T 1.41.4 1.4 1.4 0.85 — — — — based softener Soft kg/T 0.5 0.5 0.5 0.5 0.5 —— — — moisturizer Crepe ratio % 20 20 20 20 20 — — — — Weight per g/m²15.0 12.9 15.0 15.6 15.0 15.4 15.5 15.0 15.1 square meter Paper One plyμm 138 135 135 142 100 92 105 96 96 thickness All plies μm 553 540 405385 400 367 315 287 287 Number of Sheets 4 4 3 3 4 4 3 3 3 plies Drytensile Longitudinal cN/ 739 477 565 758 720 763 579 612 1397 strength25 mm Dry tensile Lateral cN/ 376 243 305 336 320 393 461 385 364strength 25 mm Softness cN/ 2.6 1.9 2.2 2.7 2.1 3.6 3.5 3.3 4.9 100 mmMMD 1/100 9.1 9.0 9.0 8.8 7.0 12.1 13.5 11.3 15.3 HydrolyzabilitySeconds 8 8 8 8 17 108 49 53 Measure- ment impossible (large) Windinglength m 23.0 23.0 30.6 30.6 23.0 24.0 22.9 10.5 32.0 Winding diametermm 116 117 117 117 117 104 95 68 104 Paper core tube mm 41 41 41 41 4143 45 41 40 (outer diameter) Winding density m/cm² 0.25 0.24 0.24 0.240.24 0.34 0.31 0.34 0.33 Roll width mm 103 104 104 104 104 108 95 108102 Stich pitch mm 116 117 114 114 114 130 105 140 110 Embossing — DoneDone Done Done Done Not Not Not Not done done done done Winding hardness(roll) mm 2.11 2.06 2.12 2.12 1.60 0.64 0.54 0.66 0.52 0.5-50 gf/cm² WCgf · 4.23 4.39 4.19 4.29 3.16 1.09 0.96 1.02 0.97 (compression workamount) cm/cm² Softness 1 to 7 6 6 6 6 6 4 4 4 3 Fullness 1 to 7 5 5 5 65 4 4 4 3 Thickness feeling 1 to 7 7 7 6 5 5 4 4 4 4 Breakage andstrength 1 to 7 7 6 6 6 6 3 4 4 7 during use

Examples according to the present invention showed excellent results inthe sensory evaluation. In addition, for water disintegrability,markedly excellent results were obtained. In addition, in comparisonwith Comparative Example 1 which is comparable in winding density toexamples, superior measurement results were obtained in terms of windinghardness and compression work amount (WC) when the toilet paper is inthe form of a roll. Further, regarding the strength, measurement resultswere obtained which shows that strength sufficient to prevent breakageduring use was secured.

Thus, the toilet paper according to the present invention gives athickness feeling providing security when used in a shower toilet, hassufficient softness, is excellent in water disintegrability, and gives asense of security for human bodies during use.

REFERENCE SIGNS LIST

-   1 Toilet roll-   10 Toilet Paper-   20 Paper tube (tube core)-   L1 Winding diameter (diameter) of toilet roll-   L2 Diameter of tube core of toilet roll-   L3 Width of toilet roll-   31, 32 Concave-   33 Valley line portion

1. Toilet paper having three or four plies, comprising: a softwood kraftpulp that is subjected to oxygen pulping and is not bleached withchlorine, and accounts for 80 to 100 mass % of fiber, and a cationicfatty acid amide-based softener, wherein the toilet paper has a basisweight of 12.5 to 15.5 g/m² per ply, a paper thickness of 120 to 150 μmper ply, a paper thickness of 400 to 600 μm as a whole of the toiletpaper, and a water disintegrability of 10 seconds or less.